In a programmable logic device (PLD), a logic circuit is composed of an adequate number of logic elements (basic blocks), and the function of each logic element and interconnections between the logic elements can be changed after manufacture. Specifically, the PLD includes a plurality of logic elements, a routing resource for controlling connection between the logic elements, and a register. The register stores data (configuration data) for defining a function of each logic element and connections between the logic elements formed by the routing resource.
A register for storing configuration data is called a configuration memory. Storing configuration data in a configuration memory is called configuration. In particular, rewriting the configuration memory with another configuration data is called reconfiguration.
A PLD in which a logic circuit can be reconfigured during the operation (the process is called dynamic reconfiguration) has an advantage of high area efficiency over a normal PLD. A multi-context system is a method of achieving dynamic reconfiguration in such a manner that configuration data read from a memory element is stored in configuration memories corresponding to logic elements or routing resources. A multi-context system is capable of performing reconfiguration of a logic circuit at higher speed than a configuration data transfer method by which dynamic reconfiguration is achieved by sequentially sending configuration data from a memory element to configuration memories corresponding to logic elements or routing resources.
Patent Document 1 discloses a programmable LSI in which reconfiguration is performed in a short time by storing configuration data sent from a dynamic random access memory (DRAM) in a configuration memory composed of a static random access memory (SRAM).